The CPU (CENTRAL PROCESSING UNIT) is undoubtedly the pivotal cog in your computer systems machinery. It performs the myriad of calculations necessary for the computer to make its decisions. The CPU does not have one standard size and interface, so make sure the Motherboard you purchase is compatible with your CPU. After years of jockeying for market share, their are currently only two major chip manufacturers, INTEL and AMD, with INTEL being the overwhelming market leader. There are four processor families on the market today. The Celeron and Pentium processors from Intel and the Athlon and Duron models from AMD.

CELERON

Intel introduced this chip as a low-cost high performance alternative to the high end Pentium III processor. Demanding "Low End" consumers as well as increased low-end competition from rival chip maker AMD has forced INTEL to continually raise the performance bar on the Celeron giving it almost Pentium III like performance at considerably lower prices. The biggest difference between the Celeron and The Pentium III is the amount of High Speed L2 cache memory the chip has access to. The Celeron generally has half the amount of memory resulting in reduced performance in some applications. Another thing that slows the Celeron down is its Bus speed. The bus is a pipeline that speeds information back and forth between the processor and the computers other components. Obviously a faster bus translates into faster processing and computing. The Pentium III has a 100MHz Bus, while the Celeron has a 66MHz bus. This only makes a difference however when their is more than 66MHz to be processed at any given time. So a thirty percent larger Bus size does not automatically result in a thirty percent increase in system performance. Celerons are generally sold today in speeds of 550MHz to 700MHz The Celeron is a Socket based chip with it's L2 cache memory directly on Die.

PENTIUM III

The Pentium III is the high end CPU currently manufactured by Intel. It runs on 100MHz Bus Speed and generally has 256K and 512K of L2 cache memory to the Celerons 128k or less. They were first introduced using the Slot 1 packaging that was being used by it's predecessor the Pentium II. This necessitated the placing of the L2 cache next to the die (the actual piece of silicon the CPU is built on) rather than placing it on the same die as the Processor which would have resulted in speedier performance. The Pentium III has since been reintroduced in a Socket 370 format that has the L2 cache directly on the Processors die. The Pentium III can be purchased as either a Slot 1 or Socket 370 CPU.

PENTIUM IV

Hold onto your hat because Intel has just announced the Pentium IV processor! It's reported to be the fastest (and most expensive) thing out their yet. If you don't mind spending as much on a chip as you would for a complete computer system then get in line for one of these "I've got the biggest baddest meanest machine on the block" chips.

DURON

The Duron is AMD's entry into the high performance, low cost, chip market. AMD and Intel are in a constant battle of trying to one up each other, both in the high and low end of the market. With the Duron, AMD once again captures the performance for price flag. The biggest difference is in the way it handles information,allowing it to enter and exit more quickly, thus avoiding bottlenecks and allowing for significantly improved performance. While the Celeron crawls along at 66MHz bus speeds the Duron operates off a 200MHz bus. This contributes significantly to overall system performance. Clock Speed on the Duron ranges from 600MHz all the way up to 800MHz The Duron uses a Socket A format to connect to the Motherboard.

ATHLON

This is AMD's high performance chip, with higher processing speeds as well as more cache built in to the chip. While the Duron tops out at 64k of L2 Cache, the Athlon (dubbed the Thunderbird) packs in a walloping 256k of L2 cache. Clock speeds on the Athlon range from 750 MHz to the current 1.2GHz. The Athlon is a significant challenger to Intel's superiority and offers a significant price to performance savings over the Intel Pentium III. The Athlon is sold either in a Slot A format or an OEM Socket A format.